Back in the vanishing past, the calculator was a staple in the Year Six classroom as it was a required piece of equipment on one of the maths papers. Now, of course, they are expressly forbidden and, as such, they can be persona non grata in many classrooms.
However, we still jealously protect our class supply of calculators. For us, even with tests looming, we try hard to keep to our principle that we are merely one step on our children's educational journey, so we endeavour to send our children to secondary with the skill of being able to use a calculator.
The reasons for this are two-fold. Firstly, the use of a calculator is an important life skill. As we battle our children on developing their understanding of methods such as long division, we hear, echoing at the back of our heads, the message from a secondary colleague, "Nah - we use calculators for that." Therefore, we want the children to be ready for that step as they get into Year Seven.
What happens when we get the calculators out for the first time? Distraction - pure and simple. To paraphrase an old song, "Those buttons are meant for pressing". The children start trying to find ridiculously hard calculations to 'beat' the calculator at. "Ha, look, I made mine get an E on it". Then one child remembers their older sibling showing them how to spell words on it. It is easy to see how this spreads round the classroom as suddenly the calculators start getting turned upside down:710, 0.7734 (if you are lucky). It is important to give them some time on this as it is only once you get through this phase, that it is time to teach the children how to use them.
For us, the mantra we teach the children is, "You put rubbish in, you get rubbish out". We teach them the locations of the important buttons and what happens if you press they '=' button more than once. Then how important it is to do calculations more than once to check they get the same answers to identify 'user-error' and then we teach them that we are going to be using these tools for checking our work.
Because this is what we use them for the majority of the time. When we are working on those fluency lessons in maths, it lets the children do their own live marking. They do a calculation using a written method and then they check the answer using a calculator. By doing this, the child knows immediately whether they need to look back at their work. This is far more efficient than waiting for an adult or peer to check. It is easy for the teacher to see if they are still doing their written methods as, if it is all done on a calculator, there is no regrouping or other notations.
We make sure that we model this in our lessons too. There are calculators available in interactive whiteboard software or online. It also lets us identify some of our 'deliberate' mistakes and model checking our work - honest.